Signaling



Patented Oct. 3, 1933 UNITED STATES PATENT OFFICE SIGNALING DelawareApplication November 20, 1929 Serial No. 408,476

Claims. I (Cl. 178--70) Long distance radio transmitters, for example,such as used in transoceanic work are customarily controlled atgeographically remote points. Impulses from the remote point are sentover land 5 lines to the transmitting station where they control relayswhich in turn control energization of the transmitter. As the lines usedin this work inherently have uniformly distributed capacity andinductance it takes appreciable time for an impulse to build up to relayoperating value at the transmitter end or" the line. This is true eventhough the current impulse builds up rapidly at first at the transmitterend, for, soon thereafter it builds up much more slowly.

For slow speed signaling this is objectionable in that the relay doesnot cause energization or deenergization of the transmitter as soon asthe impulse is placed upon the line but responds some time after,resulting, of course, in energization of lesser time value thanintended. During times of peak load, or in other words at times of highspeed signaling the same line is used which, because of thecharacteristic already discussed,vhas a tendency to prevent, due torapid reversals on the line duringhigh speed signaling, the current atthe transmitter end of the line from ever reaching a value necessary tooperate the transmitter controlled relay. I

To overcome the foregoing difficulties and to allow of the use of anordinary land line for accurate control of a transmitter according toimpulses sent out on the line is the prime object of the presentinvention. According to the invention a polarized relay is providedbetween the line and transmitter which, to give initial and immediateresponse to the beginnings of signal characters or for high speedsignaling is made responsive to rate of change of current flow on theline which, as already indicated is high when a signal is started andduring high speed signaling. For low speed signaling additional meansare provided to maintain operation of the relay when the rate of changeof current has diminished so that uniform flow of current is on theline.

The accompanying drawing which is illustrative and not limitative of thepresent invention may be referred to to good advantage in furtherunderstanding the principles outlined above and also gives by way ofexample a manner in which the invention may be effected.

Turning to the drawing signaling current impulses sent out on the landline 2 by means of keying device 4 actuate relay apparatus 6 which inturn controls energization of a transmitter 8.

former 28.

The transmitter 8 comprises a master oscillator 10 feeding energy to apushpull amplifier 12 whose output is amplified to a high degree bypower amplifier 14 and thence transmitted or radiated by suitableantenna 16, preferably of directive character. By controlling thepotential across terminals 18 the output of ampliher 12 may be variedfrom out off to zero output, to maximum output depending upon therespective connection of biasing sources 20, 22 to terminals 18.

To provide quick action at the starting and stopping of signalcharacters there is provided in relay apparatus 6 a pair of pushpullconnected electron discharge devices 24, 26 having their input coupledto the line by means of a trans- Consequently, at the starting orstopping of signal characters, when the rate of change of current flowthrough the primary of transformer 28 is high, coils 30, 32 in theoutput circuits of tubes 2 l, 26 predominate in controlling the movementof armature 34;.

For steady values of current or for lowspeed signaling coils 36, 38 areprovided in the manner shown. In order to properly terminate the line 2when coils 36, 38 and transformer 28 are connected thereacross, there isalso connected 8. terminating impedance 4O suitably designed to preventreflection. Also if desired one of the lines forming the land line 2 maybe eliminated and the corresponding ends of the eliminated line may begrounded.

More specifically when. a positive impulse is sent over the lower line2a of land line 2 by depressing key 4, because of the rate of change ofcurrent through transformer 28, vacuum tube 24 becomes conductivepulling armature 34 up thereby reducing the negative bias on amplifier12 allowing of energization of antenna 16. As 5 the rate of change ofcurrent through the primary of transformer 28 decreases, the uniformflow of current through coils 36, 38 manifestsitself by holding armature34 in the position that coil 32 pulled it. Therefore, during uniformflow of current coils 36, 38 become predominant; While, for extremelyhigh speed signaling, entire action is accomplished by coils 32 and 30,the, latter of which becomes effective for deenergizing the transmitterwhen there is a reversal of the current on the land line 2 due to theraising of key 4 to its upper contact. Under the last referred tocondition the current through coils 36, 38 is reversed which, of course,predominate in maintaining armature 34 in its lower position when therate of change of current in transformer 28 again becomes negligible.

Having thus described my invention what I claim is: i

1. In a transmitting system, a source of di rect current potential, anarmature, an electron discharge device having a coil in its outputcircuit magnetically associated with said armature, and means forconnecting the input circuit oi said discharge device to said directcurrent source whereby said armature is actuated by rate of change ofcurrent in the input circuit of said electron discharge device, and,another coil connected directly to said source and magneticallyassociated with said armature for causing movement of said armature inresponse to constant current flow from said source.

2. In a transmission system a source of keyed energy, anelectromechanical relay having a pluality of coils and an armature, anelectron dischargedevice coupling one of said coils with said sourcewhereby movement of he armature is produced in accordance with the rateof change of current flow from said source, and, connections forcoupling the other coil of said relay directly to said source wherebymovement is imparted to said armature by virtue of the steady currentcomponent flowing through said last mentioned coil.

3. In a system for transmitting intelligence by virtue of the flowofelectrical energy keyed in accordance with the intelligence to betransmitted, a transmission line for conducting the keyed electricalcurrents, an electromechanical relay having a polarized armature and aplurality of coils associated therewith, an electron discharge deviceconnected between said transmission line and one of said coils forimparting motion to 7 said armature in accordance with rate of change ofcurrent on said transmission line, and; means for connecting the otherof said coils to said transmission line for imparting a force to saidarmature according to the stemy flow of current on said line.

4. Means for keying at high speed or low speed a transmitter including athermionic amplifier from a remote point comprising, a keying circuitincluding an armature connected with said amplifier, two pairs ofwindings associated with said armature, a source of direct currentpotential located at said remote point, a transmission line forconnecting said direct current potential in series with one of saidpairs of windings, a pair of thermionic tubes having their anodesconnected together through the other pair of said windings, aninductance in said transmission line, and an inductance connected to theinput electrodes of said tubes, said last named inductance being coupledto the inductance in said line.

5 In combination, a high frequency oscillation relay device, a keyingcircuit connected therewith, said keying circuit including a source ofenergy, a contact and an armature for closing said contact under certainconditions to key said relay device, a pair of magnetic windingsassociated with said armature, a source of keying currents, means foractuating said armature at a low keying speed including a circuitconnecting one of said magnetic windings directly to said source ofkeying currents, and means for actuating said armature at high keyingspeed including a thermionic relay coupling said source to the other ofsaid magnetic windings.

JAMES L. FINCH.

